This invention is concerned with the detection of electromagnetic radiation.
The detection of electromagnetic energy is made possible because of a series of complex interactions which occur between such energy and certain kinds of materials. These interactions enable remove sensing systems to record contrasts between an observed object and its background. Recent improved detector designs based on the phenomenon of impurity band conduction (See Petroff, et al., U.S. Pat. No. 4,568,960 and Petroff, et al., U.S. Pat. No. 4,586,068) have significantly enhanced the power of the optical detectors available in the art. The output of these detectors in response to incident photons, however, depends on the total number of photons absorbed and does not provide information regarding the wavelengths of the photons which are absorbed.
It would be desirable in some applications to be able to discriminate between optical sources having different spectral contents. A need has thus developed in the art for an impurity band conduction detector which can provide spectral discrimination.